A variety of different types of electronic devices provide utility only when viewed. Examples of these types of devices include televisions, computer monitors, laptop displays, displays for cellular telephones and personal digital assistants, and tablet computer displays.
Some electronic devices that present visual images for human benefit, such as plasma screen televisions, require considerable power. Other devices which present visual images are more energy efficient, but require the use of at least one battery. The batteries are typically rechargeable, but recharging the battery is often inconvenient for the user. Some devices operate in environments in which energy is limited and therefore valuable. Consequently, minimizing power waste is an important product function.
In addition to considerations related to power consumption, there are other benefits which result from limiting operations of electronic devices to those times in which the operation provides utility. One such benefit is that the useful lifetime of the device may be extended. Thus, if an electronic device, such as a plasma screen television, has a finite lifetime expectancy in terms of hours in use, the value of the device over time can be increased by properly regulating the use of the device. This applies to low-cost devices that do not include visual displays, such as light sources. Thus, the useful life of a light inside an oven or closet can be extended if the light is turned “on” only when a person looks through the oven window or looks into the closet.
There are approaches to automatically turning a device “on” and/or “off” at appropriate times. One known technique is to monitor activity by input devices of a computer system. Thus, when there is a prolonged period in which there is no activity at a keyboard or computer mouse, a computer system may be switched to a reduced power state. Then, when the user of the computer system causes movement of the mouse or initiates a keystroke, the system returns to its fully operational state. Many televisions include “sleep” timers in which the television will turn off automatically after a particular period of time. The various known techniques for automatically changing the state of a device operate well for their intended purpose, but include limitations.
Other operational parameters of an electronic device may be adjusted without contacting the device. For example, the volume or channel of a television may be changed using a remote control unit. The unit significantly increases the convenience of making repeated changes to the operational parameters of the device. However, there may be times in which the remote control unit is not readily available, such as when the unit has been misplaced. U.S. Pat. No. 6,163,281 to Torch describes a system and method for communicating with a device using eye movement. Glasses may be specially equipped to include an emitter for directing light towards an eye and to include a sensor for detecting light reflected from the eye. A radio frequency transmitter then transmits a stream of data to a remote location, such as a receiving and processing unit for controlling a device. The stream of data may be a binary signal, such as Morse code. The patent primarily describes the sensor as being a single photocell connected to the frame of the glasses, but states that an array of sensors may be substituted, with the processor accessing the signals from each sensor in the array to create a stream of data indicating the percentage of surface area of the eye covered by the eyelid. The Torch system and method provides advantages relative to the use of the conventional remote control unit, but requires that the optical components be close to the person's eye in order to acquire reliable information.